(1) Field of the invention
The present invention relates to a process and an apparatus for peeling outer tubes from spent NaS cells, which are to be used in the disposal of spent NaS cells.
(2) Related Art
In an NaS cell, sodium and sulfur are disposed on opposite sides of a solid electrolyte tube made of .beta.-alumina, and the entire assembly is protected by an outer tube made of aluminum. Such NaS cells have been developed as cells for storing large amounts of electric power and as cells for electric automobiles. However, it is presumed that since the service life of the NaS cell is around 10 years, a huge number of spent NaS cells will come out in the future.
The present inventors have been developing techniques for disposing of such spent NaS cells. In this disposal process, the outer tube needs to be peeled from the spent NaS cell. In order to peel the outer tube, it is a conventional practice that the spent NaS cell is chucked on a lathe, cut lines are circumferentially formed in opposite end portions of the outer tube, then the cell is set at a milling machine where a middle portion of the outer tube is divided into two or three sections by axially forming straight cut lines in the outer tube with the use of an end mill, and the outer tube is peeled and removed by hand along the thus formed cut lines. However, the above process has poor working efficiency, and suffers from high equipment cost because the lathe and the milling machine are required.